[Clang][ByteCode][NFC] Misc minor performance fixes (#145988)

Static analysis flagged multiple places we could move instead of copy.
In one case I realized we could avoid computing the same thing multiple
times and did that fix instead.

Author: shafik

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -555,8 +555,8 @@ static bool interp__builtin_isfpclass(InterpState &S, CodePtr OpPC,
   APSInt FPClassArg = popToAPSInt(S.Stk, FPClassArgT);
   const Floating &F = S.Stk.pop<Floating>();
 
-  int32_t Result =
-      static_cast<int32_t>((F.classify() & FPClassArg).getZExtValue());
+  int32_t Result = static_cast<int32_t>(
+      (F.classify() & std::move(FPClassArg)).getZExtValue());
   pushInteger(S, Result, Call->getType());
 
   return true;
@@ -856,7 +856,7 @@ static bool interp__builtin_overflowop(InterpState &S, CodePtr OpPC,
 
     if (!APSInt::isSameValue(Temp, Result))
       Overflow = true;
-    Result = Temp;
+    Result = std::move(Temp);
   }
 
   // Write Result to ResultPtr and put Overflow on the stack.
@@ -1135,17 +1135,17 @@ static bool interp__builtin_is_aligned_up_down(InterpState &S, CodePtr OpPC,
 
   if (isIntegralType(FirstArgT)) {
     const APSInt &Src = popToAPSInt(S.Stk, FirstArgT);
-    APSInt Align = Alignment.extOrTrunc(Src.getBitWidth());
+    APInt AlignMinusOne = Alignment.extOrTrunc(Src.getBitWidth()) - 1;
     if (BuiltinOp == Builtin::BI__builtin_align_up) {
       APSInt AlignedVal =
-          APSInt((Src + (Align - 1)) & ~(Align - 1), Src.isUnsigned());
+          APSInt((Src + AlignMinusOne) & ~AlignMinusOne, Src.isUnsigned());
       pushInteger(S, AlignedVal, Call->getType());
     } else if (BuiltinOp == Builtin::BI__builtin_align_down) {
-      APSInt AlignedVal = APSInt(Src & ~(Align - 1), Src.isUnsigned());
+      APSInt AlignedVal = APSInt(Src & ~AlignMinusOne, Src.isUnsigned());
       pushInteger(S, AlignedVal, Call->getType());
     } else {
       assert(*S.Ctx.classify(Call->getType()) == PT_Bool);
-      S.Stk.push<Boolean>((Src & (Align - 1)) == 0);
+      S.Stk.push<Boolean>((Src & AlignMinusOne) == 0);
     }
     return true;
   }
@@ -1425,7 +1425,7 @@ static bool interp__builtin_ia32_addcarry_subborrow(InterpState &S,
 
   QualType CarryOutType = Call->getArg(3)->getType()->getPointeeType();
   PrimType CarryOutT = *S.getContext().classify(CarryOutType);
-  assignInteger(S, CarryOutPtr, CarryOutT, APSInt(Result, true));
+  assignInteger(S, CarryOutPtr, CarryOutT, APSInt(std::move(Result), true));
 
   pushInteger(S, CarryOut, Call->getType());